Recently, mobile telephones and personal digital assistants provided with an image pickup apparatus employing a solid-state image pickup device like a charge-coupled device (CCD) image sensor or a complementary metal-oxide-semiconductor (CMOS) image sensor have been gaining widespread use. Solid-state image pickup devices used in such image pickup apparatuses have become more compact in recent years. As sensors employing the video graphics array (VGA) image format (with 640×480 effective pixels), 1/10-inch-sized (2.2-μm pixel pitch) and 1/12-inch-sized (1.75-μm pixel pitch) solid-state image pickup devices are commercialized today. This has led to an increased demand for even more compact image pickup lenses to be mounted in image pickup apparatuses.
Single-element image pickup lenses are proposed as image pickup lenses suited to such requirements, because the single-element image pickup lenses are low-cost lenses and can be made more compact.
It has become a trend, these days to use lenses made of resin that are suited to mass production as lenses for forming subject images on the aforementioned image pickup devices in order to achieve a further cost reduction. A requirement for higher performance has also been met by forming resin-made lenses that offer good workability in aspherical shapes. Patent Documents 1 and 2 propose image pickup lenses employing single biconvex lenses as the aforementioned kinds of image, pickup lenses.